Seems overpriced currently, since the average creature costs less than 5
... At best you just end up with a situational quanta converter.
Defensively, it would probably need to be nearly free to make it worthwhile... offensively its a little trickier to balance but my gut says the cost needs to be quite low to make it viable.
The 2 problems I see.
1) Defensively: At best (with a cost of zero) it just recoups your lost quanta... unfortunately, you give up further card advantage to do so. Anything other than a zero cast cost makes this more or less pointless to use. Even then, card advantage is often quite precious.
2) Offensively, it has some potential, but outside of rainbow decks will be highly situational due to the relatively low probability that the opponent is using cards that would provide useful quanta to you. See
Mental Bridge|Soul Link for a discussion that is fairly relevant to this issue
Now, as a permanent or creature ability this effect is a little more useful. The key is that you don't have to give up card advantage then. With a slightly lower cost, it becomes very useful defensively.
Offensively, you still need to deal with making sure that the returned quanta is useful (again, see above link for some relevant discussion)
